The cleaning and maintenance tags are both used for cleaning, and both used for maintenance. It seems the only reason for this is that the site doesn't know they are similar, and doesn't suggest them.
I propose that cleaning be made a synonym of maintenance.
It sounds like the maintenance tag covers topics like cleaning and more. I say instead of making them synonyms just remove cleaning and expand the description of the maintenance tag to explain the broad scope of this tag.
Looking at the questions, I think it is best to create a tag-synonym, as people are still using the tags interchangeably. If this is not disputed, I will super-vote the proposal and create the synonym.
